NASA's aging crawler is about to haul 18 million pounds on its back, again

After more than five weeks of sitting on its Florida launchpad, the Artemis II rocket will head back to its hangar for some unanticipated repairs, without having launched to the moon. 

As long as the weather holds up, NASA is targeting 9 a.m. on Wednesday, Feb. 25, 2026, for the move to the Vehicle Assembly Building at Kennedy Space Center in Cape Canaveral. Four miles may seem like a short trip, but when billions of dollars' worth of hardware are at stake, every inch can feel like an eternity. 

At the center of the rollback is the U.S. space agency's crawler-transporter, a tank-like vehicle the size of a baseball infield that will carry the 322-foot Space Launch System, the Orion spaceship, and the mobile launcher. The crawler, built in 1965, has made the journey many times, hauling Space Shuttles and Apollo's Saturn V rockets, traversing over 2,500 miles. 

For John Giles, who leads the team of drivers, engineers, and technicians responsible for the old crawler, it's undoubtedly a nerve-racking time. Giles likens operating the crawler to steering an ocean liner in the dead of night on a transatlantic cruise. A new driver takes over every hour of the 12-hour voyage, he said, so no one gets sleepy at the helm.

"Every roll stresses me because of the amount of weight and the amount of value of what we're carrying," he told Mashable in 2022, shortly after a roll to the launchpad for Artemis I. 

The stacked mega moon rocket weighs some 18 million pounds. To carry the load — 50 percent heavier than it was originally designed to bear — NASA upgraded one of its two crawlers with new brakes, generators, engine parts, and bracing.

In March 2023, Guinness World Records designated that refurbished crawler, known as CT-2, as the heaviest self-powered vehicle. The crawler itself weighs 6.6 million pounds, about the same as 1,000 pickup trucks, and it runs on locomotive and large electrical power generator engines. Giles calls it the original hybrid vehicle. 

The increased load of the new rocket has taken its toll on the crawler. The treads — or as the team calls them, "shoes" — wear thin rather quickly. Technicians are having to replace two or three shoes after every roll.

NASA will broadcast the crawler's journey from pad to hangar live on its YouTube channel. Officials also will provide updates on its progress in the agency's Artemis blog. 

Once back in the hangar, teams will begin installing platforms to access an area of the rocket's upper stage where NASA recently discovered a helium flow problem. Helium is important for the rocket because it helps protect the engines and keeps the fuel tanks at the right pressure. A similar pattern apparently cropped up before the launch of Artemis I, which didn't carry any astronauts. 

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It's not clear whether engineers have diagnosed the problem yet. Prior to the rollback, mission managers had said they were looking at several potential causes, including a connection point between the ground equipment and the rocket, a valve in the upper stage, and a filter in the helium line.

Artemis II is a 10-day lunar flyby, testing the new Orion spaceship with humans aboard. Four astronauts —  Commander Reid Wiseman, Victor Glover, Christina Hammock Koch, and Jeremy Hansen — will be along for the ride. It's NASA's first crewed mission beyond Earth orbit since 1972. 

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The test flight sets the stage for a lunar landing during the next mission, Artemis III. The purpose of the Artemis program is to establish a long-term human presence on the moon before trying to survive on Mars.

If teams can address the problem quickly, an April launch might be possible. The opportunities for the month include April 1, April 3 through 6, and April 30. Other dates are likely available in May, but NASA hasn't made any launch window information beyond April available to the public.

While the rocket is in the Vehicle Assembly Building, teams will replace batteries, including those in the flight termination system, a mandatory safeguard that destroys the rocket if it veers off course or critically malfunctions during launch.